The best PCB films I ever managed to get were done by a friend who was into the offset printing business. They had film imagers at the time which could convert a CAD file into 4800dpi polyesterbase graphical film. "Flawless" edges, within reason.
2nd best I did myself using a surplus graphical camera from the same printing branch. Agfa Copyproof film, I still remember. All this kind of equipment is long since obsolete.
Wilko
